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Date: Tue, 26 May 2015 10:52:43 +0800 From: yalin wang <yalin.wang2010@...il.com> To: Jungseok Lee <jungseoklee85@...il.com> Cc: linux-arm-kernel@...ts.infradead.org, barami97@...il.com, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-mm@...ck.org Subject: Re: [RFC PATCH 2/2] arm64: Implement vmalloc based thread_info allocator 2015-05-25 0:02 GMT+08:00 Jungseok Lee <jungseoklee85@...il.com>: > Fork-routine sometimes fails to get a physically contiguous region for > thread_info on 4KB page system although free memory is enough. That is, > a physically contiguous region, which is currently 16KB, is not available > since system memory is fragmented. > > This patch tries to solve the problem as allocating thread_info memory > from vmalloc space, not 1:1 mapping one. The downside is one additional > page allocation in case of vmalloc. However, vmalloc space is large enough, > around 240GB, under a combination of 39-bit VA and 4KB page. Thus, it is > not a big tradeoff for fork-routine service. > > Suggested-by: Sungjinn Chung <barami97@...il.com> > Signed-off-by: Jungseok Lee <jungseoklee85@...il.com> > Cc: Catalin Marinas <catalin.marinas@....com> > Cc: Will Deacon <will.deacon@....com> > Cc: linux-kernel@...r.kernel.org > Cc: linux-mm@...ck.org > --- > arch/arm64/Kconfig | 12 ++++++++++++ > arch/arm64/include/asm/thread_info.h | 9 +++++++++ > arch/arm64/kernel/process.c | 7 +++++++ > 3 files changed, 28 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 99930cf..93c236a 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -536,6 +536,18 @@ config ARCH_SELECT_MEMORY_MODEL > config HAVE_ARCH_PFN_VALID > def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM > > +config ARCH_THREAD_INFO_ALLOCATOR > + bool "Enable vmalloc based thread_info allocator (EXPERIMENTAL)" > + depends on ARM64_4K_PAGES > + default n > + help > + This feature enables vmalloc based thread_info allocator. It > + prevents fork-routine from begin failed to obtain physically > + contiguour region due to memory fragmentation on low system > + memory platforms. > + > + If unsure, say N > + > config HW_PERF_EVENTS > bool "Enable hardware performance counter support for perf events" > depends on PERF_EVENTS > diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h > index dcd06d1..e753e59 100644 > --- a/arch/arm64/include/asm/thread_info.h > +++ b/arch/arm64/include/asm/thread_info.h > @@ -61,6 +61,15 @@ struct thread_info { > #define init_thread_info (init_thread_union.thread_info) > #define init_stack (init_thread_union.stack) > > +#ifdef CONFIG_ARCH_THREAD_INFO_ALLOCATOR > +#define alloc_thread_info_node(tsk, node) \ > +({ \ > + __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE, VMALLOC_START, \ > + VMALLOC_END, GFP_KERNEL, PAGE_KERNEL, 0, \ > + NUMA_NO_NODE, __builtin_return_address(0)); \ > +}) why not add __GFP_HIGHMEM, if you decided to use vmalloc() alloc stack pages? Thanks -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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